Focusing-camera.



J. BECKER.

FOCUSING CAMERA.

APPLICATION FILED JUNE 15. 1901.

1,190,623. v Patented July 11, 1916.

4 SHEETS-SHEET I.

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J.BECKEB. FOCUSING CAMERA. APPLICATION FILED JUNE 15. 1901.

1 ,1 90,623 Patented July 11, 1916.

I 4 SHEETS-SHEET Z- Wz'hzcssas L,BECKER. EOCUSING CAMERA. I APPLICATION FILED JUNE 15, 1901- 1,190,623. Patented July 11,1916.

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W'L'Zn 5 "es f fizz/elm)?" J. BECKER.

FOCUSING' CAMERA. APPLICATION FILED lUNE l5. 1901.

Patented July 11, 1916.

4 SHEETS-SHEET 4 UNITED STATES 1?ATENT oFEIoE.

JOSEPH BECKER, or wnsnmeron, nrs'rmcr or COLUMBIA.

- FOCUSING-C AMERA.

plications or patents as Case D; and the.

present specification hereinafter makes specific reference to my related applications or patents as follows: Case A, new Patent 1,178,474, issued April 4, 1916 Case B, Now Patent 1,178,475, issued April 4, 1916; Case C, now Patent 1,178,476,'issued A ril 4, 1916;

Case W, Serial No. 696,197, fied May9, 1912, as a division of the present application, Case D.

' prior Cases A, B, and

My present invention relates to optical focusers. of the type disclosed in my said C, in which the operation of focusing is reduced to the act of virtually sighting the object point to be focussed on from station points on the camera. All focusers' 1 order,

shown in my said prior Cases A, B, and C, including even the funicular focusers of Figs. 14 to 16 ofmy said Case A, comprise one or more structural elements that are pivoted; Whereas, the novel focusers herein described do, without rotations,

translations, accomplish the same final result, to wit: secure proper coordination of camera extensions with ray inclinations. In

however, to connect my present invention logically with the basic invention disclosed in my said Case A, I am first showing a special pivoted mirror form of focuser which :closely resembles the focuser shown in. my said: Case B and is easily converted into a form containing no rotating elements whatever. I. In the accompanying drawings: Figure 1 1s a side elevation of a camera in which the exterior relatively movable images are ivoted mlrror,

formed by ,a fixed mirror, a

is aview lookto left in Fig. 1, showing how the optical parts would appear with both mirrors fixed in parallel relation and the lens divided to produce displacements" of the images by shifting one lens section by the other; Fig. 3 is a perspective view of an equivalent combination made of glass prisms; Fig. 4=is a side elevationof a, camera,

Specification of Letters Patent.

Application filed June 15, 1901..

District of C0lumbia,1- have intwo laterally separated 1 by means of pure- 5 Patented July 11, 1916.

Serial No.64,722.

provlded with the optical elements of Fig. 3. Fig. 5 is a sectional view of an arrangement inwhich the relatively movable images are-produced by means of two diminutive cameras and a prism; Fig. 5 is a view looking in the direction of arrow 18, Fig. 5, the camera proper being omitted; Fig. -6 is a sectional View of another form in which the relatively movable images are produced by means of divergent lenses and a prism;

Figs. 7 and 8 are variations of Figs. 5 and 6,

respectively; Fig. 9 is a side camera in which the relatively movable images are formed by two eccentric lens elements and a screen; FigsQlO and 11 are diagrams illustrating the optical principles involved in the focusers of Figs. 1 to 4.

The specificform ofmy invention that I,

have elected to "support the more specific claims of the present application, CaseiD, is that illustrated in Figs. 2 to 4 with the raid of Fig. 1. The forms of Figs. 5, 5, 6,7,8 'and 9, all characterized by the fact that the relative movements of the focuser elements are the same in direction and extent as the focusing movements of the camera relatiye lens and camera plate or film, constitute the subject-matter of a separate application, my said Case I p The fundamental principle of the mirror type is made clear in Fig. 1, where M and N represent two parallel mirrors and S a preferably of short negative focus. mirrors form, of any object I, an image I, which is shifted up and back of I through a distance 11 or 2d. equal to twice the distance d between the planes of the two mirrors exactly as in Fig. 13 of my said Case A, Fig. 9 of my said Case B, and Fig. 8. of my said Case 0.

Lens, S, forms of object I and of its image, I, small images, nearly in the principal focal-plane of the lens the efi'ect being substantially the same as illustrated in Fig. 9 of my said Case B,

and in Fig. 8 ofmy said Case 0. Mirror, N

lens," The elevation of a v '5 21', which are very I beingopaque, must conceal all of image z,

that lies behind it; but, it will simpllfy matters to first consider this mirror. as being of illimited extent, but transparent as well as reflecting. In this case both images, '5

and i, will be perceived in full at the same timeand the apparent distance betweenitheir centers can be seen to be almost .inversely roportlonal to the distance of point, I, from ens,

S; that is to say; the distance from the I center'of z' to the center of a" will appear to bevery small or practically m'Z when I is must be increased by very distant, and it becomes gradually larger as I approaches.

Images, 2' and i, of point, I, can always be brought into register or coincidence by moving some part of the optical combination and the extent of motion required to secure coincidence corresponds to the distance between said images. On the other hand, when a camera in focus on infinity is to be .focused on a point that is close, its depth a certain amount which is greater as the object comes closer and this increase in depth is also very nearly inversely proportional to the distance of the object. Hence, if a camera is mounted in combination with an optical arrangement,

such as that o Fig. 1, the motions of the camera to keep it in focus on a moving point, I, will correspond to those that must be made in the optical arrangement to keep the lmages, 11 and i, in coincidence and this porting part ofthe camera.

correspondence can be secured by the trial adjustment of proper mechanical connec-.

tions, as fully explained in my said Cases -A, B, and C. In the-mirror forms of my said Cases A, B, and C I secure coincidence by pivoting either one or both of the mirrors. Thus by pivoting mirror, M, forinstance, on pivot, 34, image, I, can be made to move around to I", along an are I I" whose center is at 34 Where mirror N forms the image of pivot-34. As the full size image I moves to I back of and into alinement with the object point I, the reduced image i of I, at the same time moves down and back of i. 1 The connection between the optical elements and the camera parts in Fig. 1 to produce the rotation is established through an arm 35 fixed to mirror M, a link 36, a lever 37 and a link 38 connected to that part '10 of the camera which holds the plate or film holder. The lever 37 is pivoted at 39 to an arm 40 mounted on the lens sup- Now suppose the link 38 to be'removed so that the mirror M may be kept fixed in its parallel relation to mirror N. The full size image I will then be invariably fixed with relation to its object I, and image coincidence, for the eye at 75, can no longer be secured except by relative displacement of the reduced images'z and i, as by dividing lens, S, diametrically on. the vertical plane perpendicular-to the mirrors and by makingits thus disunited halves slide by each other. In this case the mirror N is preferably made totally reflecting or n'on-translucent,'and one half of it is suppressed so that the remaining half N, Fig. 2, with its corresponding left half S of v the lens may'serve exclusively for one-half 'ofimage, 71; the other or right half S of the lens then serves alone for the complementary half of image, 11.

and exclusively An expensive but simple and easily understood form of this device is shown in perspective Fig. 3, where the fixed parallel mirrors, M N are the end faces of a glass prism, 10, and the divided lens is formed by grinding a concave, half in the prism and half in an adjacent glass block, 11. Prism,

The plate or film holding part of the I camera is designated by 1 and the observers eye by 76.

In cheaper forms the object mirror is made so as to project beyond the median plane as indicated for object mirror M at 12 in Fig. 2, and the divided lens is made accurately enough by splitting a common minus lens and smoothing its split edges.

As Figs. 2 to 4 have become the most important figures of the present application, Case D, the complete theory involved is illustrated in the supplemental diagram Figs. 10 and 11. Fig. 10, with the two half lenses S, S held to act as a single lens, illustrates the optical principles involved when the mirrors M and N are parallel and the mirror M is pivoted at 34. The object point to be sighted on being at I, its image, after reflection in mirror M and then in mirror N, is at I, where the vector II is perpendicular to the mirrors and equal to 2d or twice the distance d between their parallel reflecting planes and this, as shown in Fig. 13, of my said Case A, is true for all possible distances of the object point I.

As clearly seen in Fig. 11, the nearer and .movable lens half S of the divided lens has its principal foci at E and G and its almost coincident nodal points may be considered as merged in one point C. Similarly, the farther and here stationary half lens S, Fig. 11', has its .principal foci at E. and G and its two nodal points roughly merged in center C. In Fig.'10, where the distances'EE, CC, and G i are all three m'l, the two half lenses act as a single lens. to form an image {i of I and an image 11 of I. By turning the mirror M clockwise on its pivot 34 through an angle alpha (or), as indicated by arrow 17,- the image I is caused to turn counterclockwise along the arc II, whose center is at 34' (which is the image of 34 in N), through an angle beta prime ((5'), which equals beta (6), or twice angle .alpha (20:). v down along arc II" to I, where-it appears alined with I so that its image z" must likewise have moved down to a position a trifle This brings image I back of This,

6- tionary half 40 as G" images -within'flth observers eye.

in accordance with the principles of my said Case A, makes pivot 34. correspond to point "A in'the theoretical form, Fig. 23, of my said Case A. See also Fig-.10 of my said Case A, where O corresponds to the present image I". a

Fig. 11 illustrates the optical principles involvedwhen image coincidence is secured,

in the combination of Fig 1, by leaving the mirrors parallel and lowering the nearer half lens S as "indicated" in Fig. 2;, The downward displacementbf the half lens S. necessary to secure coincidence is indicated inFigfll by GG", which is determined by 15 producing the lineIO toG', where it meets thegvertical'focal plane through G. The half lensS having been lowered by this amount,asillustratedin-Fig. 11, forms the imaged of I in theaxis Ef'Gff of the sta- S directly behind '11, which'is left as an unblacked dot for clearness.

The pivot 34: of Fig. 10'having completely disappeared in Fig. 11,]the ray inclinationso determined by angle. gamma in Fig. 11 are which is smaller than angle beta ((5) 1n Flg.

first reflected image is at 0.

corresponds This-apex c to pivot A in the theoretical form, Fig. 23, of'my said Case A. One sta said second mirror image. of station point 35" O. Point O" as a pomt'of the'stationary half lehs S admits and transmits the direct ray IC"G and the same point C considered as a point of'the lowered lens S- ad- H I C and transmits it so that the lowered lens acts to remits the inclined ray 1 fract the incident ray'I'C'f at O", through an angIeHIOVI- or gamma prime which is variable at will by varying the distance O C When CC'fis mil angle'gam- 1 ma prime-(7') is m'l, which can only be true whenvector II" is at infinity.

l in h h coincidence is shamed .by relatlv motion of the-mirrors the l may .be

lens of infinite plate glass. Considered as a lens, such. a

' plate forms the image of any object within Y and of the samesize as the'object itself, and hence the images,i and i, of object, I, and'of its" image, I, coincide with-such object and tion as their originals.

is no, real coincidence" of images {except of Fig. 1 turning mirror,.M, clockwise causes image, I, to move from I to I" and thls 1n turn causes the retinal images to meet and co- ;lens, ,4, and screen, 5. SCIlPtlOIl,

one over the other 1n the same vertlcal 10, as its apexisat of, which is the second reflected image of center C",1whose station point is. situated at c, which is the farther away from or closer The continuity d 1fspense d' with altogether which 50 amounts to the same thing-as employing a focus,'th at is, a piece of-plainl thef flenses, the. retinal "-Thus incide. My object is in all cases sufliciently and fully attained by nothing more than this coincidence wlthin the observers eye.

which is provided with means (not shown) for adjusting the depth or distance between L and H. 011- the lens holding frame are fixed two similar diminutive cameras or finders, F and V, each comprising a case, 3,

these finders are supposed tobe plane. On the plate holding frame, H, is fixed a prism, P, which, as seenin Fig. 5 is set to apparently overlap one-half of the lower '1' fi l- 1 7, the part of finder, V, which lies behind V. For the observer, whose eye is at the prism is by refraction apparently dropped to V and in its original-place is seen the half,-F,' of the upper finder, F. If a horizontal bar beviewed in the finders it will form-in the upper dropped by refraction to 9' and the same bar will form in 'the'lower 'finder an image, 10, 11,'part', 10, -"of which-appears directly as seen in- Fig. 5 and part, 11 (dotted), as dropped to 11. 3

By varyingthe depth of the camera the half image, 9, can be moved up and down and bemade to register lwith, half mage, 10, and form therewith a continuous mage. On the other hand, if the original bar moves to the camera,

the half images, 10 and 9,

separated or approached because their orig- -inals, 10 and 9, on screens,

5, are separated when the object approaches,

' of the image, therefore, depends simultaneously upon the' distance of theobject and thedepth of the camera; and I have discovered that in rect observation, to secure exact c'o'rrespon ence between the camera and the focuser' E01 two d fferent will be eitherand vice versa,

' lens, bellows and plate holder of a camera,

To facilitate the de-' finder an image, 8, 9, the right half, 9, .of which will be this case, as in the preceding, the parts can always be proporf tioned and adjusted, by calculatlon or by dl- "v distances of the object polnt. 1 The-great advantage of this form is that 1n it the. mechanical connections withthe ca eral 'are as; simple. as they can well be.

i are large:1n"diameter as compared with their focal length, the screens, 5, maybe omitted. No screens can be used with minus lenses, b ut in this case the motions are reversed. Pili ghave secured this reversal by simply connect'ng the parts is movedfrom 37 to 39 the two images shown as round dots are seen to red that each produces on the screen along. line 47,

as shown in Fig. 6 so the prism shall move with the camera lens and the finder lenses with the camera plate holder. When lenses without screens are used it is better to add prisms, p, '9, Figs. 7 and 8 which permit of securing a better field. I

In Fig; 8 by theuse of reversed prisms, the arrangementis made symmetrical and. optically better, tions are less than in the preceding forms, and colorations are avoided by the reversal of prisms. In all the prismformsso fardescribed the indications depend solely on the depth of the camera and are not appreciably affected by lateral displacements orv vibrations. This is a great advantage.

In Fig. 9 I show a formin which thecoincidence of the images is real, as well as apparent". externally on its plate holder a screen, 29, and on its lens holder .a pair of prisms having one face sphericaL These prisms. act like small eccentric lens elements, that is, like lenses of considerable depth or" focus .so an image which remains clear through considerable movements of the screen. Thus by moving the screen, 29, from 37 to 39 the image formed by the upper lenticular prism may be considered as moving with the screen, but that is, ,to.have an up and down motion on the screen. Similarly, the image formed by the lcwer lenti'cular prism also moves down and up as the screen is reciprocated between 37 and 39. W hen both images are observed together and screen, 29,

first approach until they meet at 43 and then separate. 'By g ving the prisms an angle and a separation that will make their refracted rays cross like those of the camera lens and by giving them about the same curvature as the lens, the prismatic arrangement will. by ceincience or separation of images indicate whether the camera is oris not in focus on a given object. One disadvantage-of this form as compared with the others is that it does not indicate directly in which direction the camera may be out of focus, unless the images are identified by momentarily covering one of the two prismatic lenses..

All the devices described are combined to produce eventually two retinal images which may be relatively moved within the observers eye and there brought into actual coinci- 'NOTE-1.Tl1e correspondence that must exist. between focusing-displacements of the camerapai'ts or image distances on the one hand, and the relat1vev inclinations of the two sighting directions on the other hand, are subject to the principles set forth 1n Figs. 23 and, 2 4: of my said Case A, and

because in it the refrac- I will be Fig. 37 of my said Case A.

The camera shown dotted carries 1 have no efiect on locating the image.

-mirror N, the observer IIOTE 5.The fact that a half lens to .Ql ohn Dollond, who substituted two half "sop/Meal Transactions, vol.

door do.

v disclosures in my said Case A thecam present Fig. 4 can always. be plotted and constructed to I yield an a-ll point correspondenc but it is more simply made, as in my said Case C, to secure only 2-point correspondence.

N on: 2.Where the lens is to serve as a true finder lens the lower mirror M", Fig. 3, should be made much larger than shown, as

uiteevident in view of the disclopage 16, and

with the'aid'of shah sure ma e in lines 58 to 78,

New 3.-VVherever.I speak of an image as being formed I use this term .as it is always used, in the science of optics, without reference as to how much or how little of the formed' imageJ-is visible, for this varies with the position-of the observers eye and with details of construction that Thus in Fig.- 7 of my said Case A, where 0 represents an image formed by the plane can see more and even all of this image 0 bysimply shifting his eye-to the left. Thi isin accordance with the oldest terminology. of the'science as proved by An. EZementmy Treatise on 0; zi'ics designed for-fl e use the cadets of the United States Mints; Academy by C. Bartlett, A. Mi, o

resscr of eXpe mental philosophy in the-Academy, ll. 1.,

.66 and 67. Nora 4.-Every mi lens, half lens, prism, shown in my gs. 1 to 11 and co sidered per as, is an image forming devic- 1889, article 57,1313.

as complete an image as a fulllens was la downas an optical principle, in 1754, by

lenses for the two full lenses originally used in the Bouguer heliomete'. See the Pki'o L8, part 2, or the year 17 54: London, 1755, page 552, servation 1.

Nora 6.-Lalande Paris, 1771, vol. 2, plate 26 (copy at the brary of Congress) shows in Fig. 186 the two'lens heliometer of Bou uer and in Fig. 187 the now well known divided lens equiva lent of Dollond; but all these lenses are convex and I believe that I 'am' the first to make or use a divided lens that is divergent instead of convergent.

Nors'i-I am aware: first, that each of theop'tic'al focusers shown in my Figs. 1 to 9', is. virtually a short base range-finder of the typehaving its relatively short base line in the instrument with means for forming two simultaneously visible and relatively movable "object point images of 'the one object point to be focused on; I am aware secondly, that two image in his Astroaomee,

' era, of two fixed mirrors,

one-half of. which is adapted to view the obj ject directly and the otherlha'lf' adapted to H- .view it by reflection iii-the mirrors,

'20 1 elements to. cause slide so any object whose direct images apparently-register shall be in focus 3. The combination aware, thir y,

cal E 'rtgiaeers, rowed M ge, London, J anuary1896, pa es 33 to 78", plates .l to 12; I am that fthe fsaid ..,Barr and Stroud 'articlefunder theihead i-Methods of producingalignment pages 39 and 40, Figs. 17 to 20, shows and discusses various methods of producing the said two relatively movable images,

Fig.*17, or a sliding lens 111 Fig. 18, or a sliding prism fore I; do not claim any matter so shown or :previouslydisclosed as by a pivoted mirror in in Figs. 19 and 20; and thereby others.

I. v 7 That I claim as'my invention and desire to secure byLetters Patent 1s:-

v 1. The combination with a focusing camand a divided lens,

I and connectionsbetween-tliecamera and the lens the latter to relatively and reflected era, 'divided 'lens, one-half of i2. i-The' 'combination. with a focusing camofrtwo ,fixed parallel mirrors, an a which is adapted to :view *one part of -theobject directly calnera in focus on an "object A 40 -cramera, comprising imag adapted to receive, transmission, two

and the-other half adapted to 'view'the complementary partoi the object by reflection 1n the mirrors, and connections between the camera and the lens elements to cause the latter to relatively slide so any object whose" direct and reflected images apparently registe'r shall be *i-nfocus in the camera 'w itha photographic camera comprising relatively movable parts adapted tobe relati-vely moved to set the point of the camera field; of an optical'focuser, for said forming elements and then collect for final emittedfrom the said object; point toward sion to I the eye from two difierent but simultaneouslyyising the distance of the said object pointy indicating, positionf fori I hand, and the said relatively movable camible object P011117 images whichhave a relativeposition duoed in the initialray inclinationsbychang- 5'5 a dfocuser comprising, moreover, relatively translatable focuser elements whose translatory or rectilinear 'di' placement; is adapted produce changes in"the1 .relative posltion of; the said two. to perobject point images,

" 'ages, at will,-int o :a characteristic relative osition that-has been selected as the focusthe camera strucbetween the said relatively tural connections translatable focuser' elements on the one era camera in focus 7 camera field; of an optical focuser, for said 7 camera, comprislng lmage forming elements 9 distinct and diflerently i 'cted groups of rays-which, are reallyi two- 'separated stations otithe said focuser v and which are collected for final transmis-v as being 1 virtually. emitted that varies with variations proparts on the'other hand to insure that to each relative position of. the camera parts shall correspond'only one angular value of ray inclinations at their origin in the said object when the said two relatively" movable object point images of such object point --have been brought into the said character istic focus-indicating relative position.

- 4. The combination with a photographic camera comprising relatively movable parts adapted to be relatively moved to set the on an object point of the and then collect for final adapted to receive,

distinct and difierently transmission, two

directed groups of rays which are really 1 elements images, to permit *ofibringing said two obat \jvill, into a characterject' point images, istic relative position that has-been selected as the focusing-indie ting position for the camera structural connections between the said relatively translatable focuser elements on the one hand, and the said relatively movable camera parts on the other hand to insure that to each relative position of the camera parts shall correspond only one angula'r value of ray inclinations at their originin the said object point when the said two' relatively movable. object point images of such object pointhave been brought into theisaidjcharacteristic focus-indicating rela tive posit-1 11;; said grelatively translatable focuser'. elements consisting in the relatively movable parts of a divided lens.

- The combination with a photographic camera comprising relatively movable parts adapted to be relatively moved to set the camera in focus on 'anoject point of the camera field; of an optical focu'ser, for said camera, consisting in a range finder of the type having itsbafse line on the camera; separated and relatively fixed mirrors for determining the two end stations of sai base line; means coeperating with the said fixed mirrors for forming two proximate and simultaneously visible f the images 0 said object'point showing it as viewed VII- ,tuallyfrom the said two end stations; such image forming means comprising relat vely moreover,

or rectilinear displacemovable optical elements whose relative mo- 1 YB i 1,190,628

tions are adapted to cause a relative motion camera parts shall correspond only one relaof the said two object point images; and tlve position of the said relatively movable structural connections established between focuser parts.

the said relatively movable camera parts on JOSEPH BECKER. 5 the one hand and the said relatively movable Witnesses:

focuser parts on the other hand to insure MARY E. Cownm,

that to each relative position of the said FRY E. PADGETT. 

